This invention relates generally to the assembly of a stack of two or more semiconductor integrated circuits.
It is known to form stacks of chips in integrated circuits. By positioning each chip in a stack and bonding them in face-to-face alignment, the distance for signals to travel from one chip to another may be reduced, resulting in faster circuits. Moreover, the stacked chip occupies less space than the individual chips (better form factor due to three dimensionality)
Commonly, stacked chips are interconnected by dielectric bonding, adhesives, or copper bonding. Wire bonds are used to electrically couple one chip to the other.
In order to combine the two integrated circuits, generally a pick and place machine is needed to position one chip precisely on the other. Adhesive adherement may also be necessary. Thereafter, the chips must be electrically bonded together, for example, using wire bonding.
Currently, logic circuits such as integrated microprocessors and memory chips are sold separately and then coupled together on a printed circuit board called a motherboard. Because of the spacing between these devices, a delay time may be induced due to the resistance and capacitance of the interconnection.
Thus, there is a need for better ways to couple integrated circuits together including, for example, logic devices and memory chips, as well as other devices.